- Continuous slurry plug flow Fe/ppm Pd nanoparticle-catalyzed Suzuki-Miyaura couplings in water utilizing novel solid handling equipment
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Herein are reported initial efforts to develop a generally accessible flow process, applying a heterogenous nanocatalyst to aqueous micelle-enabled Suzuki-Miyaura coupling reactions. Also disclosed is a new engineering solution (i.e., a self-draining back pressure regulator), which, when applied, enabled 1.5 hours of continuous operation leading to the production of 20 grams of a pharmaceutical intermediate.
- Chang, Jim,Gallou, Fabrice,Lipshutz, Bruce H.,Plummer, Scott,Robinson, Richard I.,Smith, Marie,Wood, Alex B.
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supporting information
p. 7724 - 7730
(2021/10/12)
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- Three-Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes
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Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
- Cho, Seoyoung,McLaren, E. J.,Wang, Qiu
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p. 26332 - 26336
(2021/11/10)
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- Photocatalyzed Transition-Metal-Free Oxidative Cross-Coupling Reactions of Tetraorganoborates**
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Readily accessible tetraorganoborate salts undergo selective coupling reactions under blue light irradiation in the presence of catalytic amounts of transition-metal-free acridinium photocatalysts to furnish unsymmetrical biaryls, heterobiaryls and arylated olefins. This represents an interesting conceptual approach to forge C?C bonds between aryl, heteroaryl and alkenyl groups under smooth photochemical conditions. Computational studies were conducted to investigate the mechanism of the transformation.
- Music, Arif,Baumann, Andreas N.,Boser, Florian,Müller, Nicolas,Matz, Florian,Jagau, Thomas C.,Didier, Dorian
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supporting information
p. 4322 - 4326
(2021/02/11)
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- Synergistic Pd(0)/Rh(II) Dual Catalytic [6 + 3] Dipolar Cycloaddition for the Synthesis of Monocyclic Nine-Membered N,O-Heterocycles and Their Alder-ene Rearrangement to Fused Bicyclic Compounds
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The catalytic construction of a monocyclic medium-sized N,O-heterocyclic ring represents a formidable challenge in organic synthesis. Herein we report the synergistic palladium(0)/rhodium(II) dual catalytic cycloaddition of vinylpropylene carbonates with N-sulfonyl-1,2,3-triazoles to afford monocyclic nine-membered N,O-heterocycles. The catalytically generated 1,6-dipole-equivalent zwitterionic π-allyl palladium(II) complex and the 1,3-dipole-equivalent α-imino rhodium(II) carbenoid intermediate react with each other in a formal [6 + 3] dipolar cycloaddition to furnish nine-membered oxazonines, which can be transformed into cis-fused [4.3.0] bicyclic compounds via a transannular Alder-ene rearrangement. The tandem one-pot cycloaddition/Alder-ene rearrangement sequence is also possible.
- Lee, Kyu Ree,Ahn, Subin,Lee, Sang-Gi
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supporting information
p. 3735 - 3740
(2021/05/29)
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- Electro-Olefination—A Catalyst Free Stereoconvergent Strategy for the Functionalization of Alkenes
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Conventional methods carrying out C(sp2)?C(sp2) bond formations are typically mediated by transition-metal-based catalysts. Herein, we conceptualize a complementary avenue to access such bonds by exploiting the potential of electrochemistry in combination with organoboron chemistry. We demonstrate a transition metal catalyst-free electrocoupling between (hetero)aryls and alkenes through readily available alkenyl-tri(hetero)aryl borate salts (ATBs) in a stereoconvergent fashion. This unprecedented transformation was investigated theoretically and experimentally and led to a library of functionalized alkenes. The concept was then carried further and applied to the synthesis of the natural product pinosylvin and the derivatization of the steroidal dehydroepiandrosterone (DHEA) scaffold.
- Baumann, Andreas N.,Dechent, Jonas,Didier, Dorian,Jagau, Thomas C.,Müller, Nicolas,Music, Arif
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supporting information
(2020/07/04)
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- Catalytic Friedel-Crafts Reactions on Saturated Heterocycles and Small Rings for sp3-sp2 Coupling of Medicinally Relevant Fragments
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gem-Diarylheterocycles display a wide range of biological activity. Here we present a systematic study into the formation of 4- to 6-membered O- and N-heterocycles and cyclobutanes bearing the diaryl motif through a catalytic Friedel–Crafts reaction from the corresponding benzylic alcohols. 3,3-Diaryltetrahydrofurans, 4,4-diaryltetrahydropyrans, 3,3-diarylpyrrolidines, 4,4-diaryl-piperidines, as well as diarylcyclobutanes are examined, with results for 3,3-diaryloxetanes and 3,3-diarylazetidines presented for comparison. Three catalytic systems are investigated for each substrate [Ca(II), Li(I) and Fe(III)], across preinstalled aromatic groups of differing electronic character. In most cases examined, the diaryl product is obtained directly from the alcohol with good yields using the most appropriate catalyst system. In the absence of a nucleophile, the olefins from the 5- and 6-membered substrates by elimination of water are obtained under the same reaction conditions.
- Croft, Rosemary A.,Dubois, Maryne A. J.,Boddy, Alexander J.,Denis, Camille,Lazaridou, Anna,Voisin-Chiret, Anne Sophie,Bureau, Ronan,Choi, Chulho,Mousseau, James J.,Bull, James A.
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supporting information
p. 5385 - 5395
(2019/06/24)
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- Oxidative C–H alkynylation of 3,6-dihydro-2H-pyrans
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Current synthesis of α-substituted 3,6-dihydro-2H-pyrans dominantly relies on functional group transformation. Herein, a direct and practical oxidative C–H alkynylation and alkenylation of 3,6-dihydro-2H-pyran skeletons with a range of potassium trifluoro
- Zhao, Ran,Feng, Guidong,Xin, Xiaodong,Guan, Honghao,Hua, Jing,Wan, Renzhong,Li, Wei,Liu, Lei
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supporting information
p. 1432 - 1434
(2019/03/28)
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- Phenoxy-Dialkoxy Borates as a New Class of Readily Prepared Preactivated Reagents for Base-Free Cross-Coupling
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One of the most useful chemical transformations of organoboronic acids is the Suzuki–Miyaura cross-coupling reaction. Although it has vast application, it possesses some limitations: boronic acids can be difficult to quantify accurately due to their tendency to form oligomeric anhydrides and they must be activated under basic conditions. To address these problems, a new class of boronic acid derivatives is described. Phenoxy-dialkoxy borates are prepared under mild conditions and show good solubility in common organic solvents. These adducts can be used in base-free metal-catalysed cross-coupling reactions, including orthogonal reactions with MIDA boronates and trifluoroborates.
- Paladino, Marco,Boghi, Michele,Hall, Dennis G.
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p. 6566 - 6570
(2019/10/22)
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- Synthesis method of dihydropyran derivative
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The invention discloses a synthesis method of a dihydropyran derivative. The method comprises the steps that an aldehyde compound and 2-aryl propylene are subjected to an one-pot reaction in a dimethylsulfoxide solution system containing persulfate, and thus the dihydropyran derivative is obtained. The method jointly constructs dihydropyran ring with the carbonyl provided by aldehyde compound, thepropenyl provided by 2-aryl propylene and the methyl provided by dimethylsulfoxide, the synthesis method is achieved through the one-pot way, the reaction condition is mild, a catalyst does not needto be added, the selectivity is good, the yield is high, and the synthesis method is beneficial for industrialized production.
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Paragraph 0049; 0067; 0068; 0072
(2018/09/12)
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- Highly enantioselective organocatalytic oxidative kinetic resolution of secondary alcohols using chiral alkoxyamines as precatalysts: Catalyst structure, active species, and substrate scope
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The development and characterization of enantioselective organocatalytic oxidative kinetic resolution (OKR) of racemic secondary alcohols using chiral alkoxyamines as precatalysts are described. A number of chiral alkoxyamines have been synthesized, and their structure-enantioselectivity correlation study in OKR has led us to identify a promising precatalyst, namely, 7-benzyl-3-n-butyl-4-oxa-5-azahomoadamantane, which affords various chiral aliphatic secondary alcohols (ee up to >99%, krel up to 296). In a mechanistic study, chlorine-containing oxoammonium species were identified as the active species generated in situ from the alkoxyamine precatalyst, and it was revealed that the chlorine atom is crucial for high reactivity and enantioselectivity. The present OKR is the first successful example applicable to various unactivated aliphatic secondary alcohols, including heterocyclic alcohols with high enantioselectivity, the synthetic application of which is demonstrated by the synthesis of a bioactive compound.
- Murakami, Keiichi,Sasano, Yusuke,Tomizawa, Masaki,Shibuya, Masatoshi,Kwon, Eunsang,Iwabuchi, Yoshiharu
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supporting information
p. 17591 - 17600
(2015/02/19)
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- Catalytic ring expansion of vinyl oxetanes: Asymmetric synthesis of dihydropyrans using chiral counterion catalysis
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Acid Showdown! The first catalytic ring expansion of vinyl oxetanes to 3,6-dihydro-2H-pyrans is described. Copper(II) triflate emerged as the best catalyst for this new transformation, which has broad scope as demonstrated by the eighteen examples included. The symmetric vinyl oxetane substrate can be asymmetrically desymmetrized when using either chiral Lewis or Bronsted acids as catalysts. Copyright
- Guo, Boying,Schwarzwalder, Gregg,Njardarson, Jon T.
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supporting information; experimental part
p. 5675 - 5678
(2012/07/03)
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- Synthesis of cis-3,4-diarylpiperidines and cis-3,4-diaryltetrahydropyrans
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Substituted cis-3,4-diarylpiperidines and cis-3,4-diaryltetrahydropyrans are synthesized in modest overall yields starting from 4-aryl-1,2,5,6-tetrahydropyridines and 4-aryl-1,2,5,6-tetrahydropyrans via the following sequence: (1) pinacol-type ring contraction having the?combination of m-chloroperoxybenzoic acid and boron trifluoride etherate, (2) Grignard addition with arylmagnesium bromide reagents and followed by boron trifluoride etherate-mediated intramolecular ring-expanded rearrangement, and (3) hydrogenation with hydrogen on 10% palladium-activated carbon. A facile synthesis of 3,4-diarylpyridines was also described by base-induced aromatization.
- Chang, Meng-Yang,Lin, Chun-Yu,Hung, Ching-Yi
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p. 3312 - 3320
(2007/10/03)
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- New synthesis of 3-aryl-2,5-dihydrofurans
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We present a straightforward synthesis of 3-aryl-2,5-dihydrofurans by ring contraction of 4-aryl-3,6-dihydro-2H-pyrans with the repeated treatment of MCPBA and BF3-OEt2. The building block 3-aryltetrahydrofuran-3-carboxylic acid with
- Chang, Meng-Yang,Lin, Chun-Yu,Pai, Chun-Li
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p. 1941 - 1948
(2007/10/03)
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- SYNTHESIS OF SUBSTITUTED 5,6- AND 3,6-DIHYDRO-2H-PYRANS BY ACID CONDENSATION OF ISOBUTYLENE AND α-METHYLSTYRENE WITH ALIPHATIC ALDEHYDES
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2,4-Disubstituted dihydropyrans, isomeric with respect to the position of the double bond, were obtained by the reaction of isobutylene and α-methylstyrene with formaldehyde and aliphatic aldehydes.
- Romanov, N. A.,Kantor, E. A.,Karakhanov, R. A.,Rakhmankulov, D. L.
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p. 351 - 354
(2007/10/02)
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- PRODUCTION OF SUBSTITUTED 5,6- AND 3,6-DIHYDRO-2H-PYRANS FROM 4,4-DIMETHYL- AND 4-METHYL-4-PHENYL-1,3-DIOXANES AND CARBONYL COMPOUNDS
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2,4-Disubstituted and 2,2,4-trisubstituted dihydropyrans, isomeric with respect to the position of the double bond, were obtained by the reaction of 4,4-dimethyl- and 4-methyl-4-phenyl-1,3-dioxanes with aldehydes and ketones.The effects of temperature and of the amount and nature of the catalyst on the direction and selectivity of the reaction were investigated.
- Romanov, N. A.,Kantor, E. A.,Musavirov, R. S.,Karakhanov, R. A.,Rakhmankulov, D. L.
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p. 1576 - 1581
(2007/10/02)
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